package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisConstants;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.CACHE_SHOP_KEY;
import static com.hmdp.utils.RedisConstants.CACHE_SHOP_TTL;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private CacheClient cacheClient;
    @Override
    public Result queryById(Long id) {
        //缓存穿透
       // Shop shop = queryWithPassThrought(id);
       // return Result.ok(shop);
        // 解决缓存穿透
        Shop shop = cacheClient
                .queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

        // 互斥锁解决缓存击穿
        // Shop shop = cacheClient
        //         .queryWithMutex(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

        // 逻辑过期解决缓存击穿
        // Shop shop = cacheClient
        //         .queryWithLogicalExpire(CACHE_SHOP_KEY, id, Shop.class, this::getById, 20L, TimeUnit.SECONDS);

        if (shop == null) {
            return Result.fail("店铺不存在！");
        }
        // 7.返回
        return Result.ok(shop);
    }
    public Shop queryWithMutex(Long id){
        String key = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        if (!StrUtil.isBlank(shopJson)) {
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        if(shopJson!=null){
            return null;
        }
        //4实现缓存重建
        String lockKey = "lock:shop:"+id;
        Shop shop = null;
        try {
            boolean isLock = tryLock(lockKey);
            if(!isLock){
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            shop = getById(id);
            if (shop == null) {
                stringRedisTemplate.opsForValue().set(key,"", RedisConstants.CACHE_NULL_TTL, TimeUnit.MINUTES);
                return null;
            }
            stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop), RedisConstants.CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }finally {
            //释放互斥锁
            unlock(lockKey);
        }
        return shop;
    }
    public Shop queryWithPassThrought(Long id){
        String key = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        if (!StrUtil.isBlank(shopJson)) {
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        if(shopJson!=null){
            return null;
        }
        Shop shop = getById(id);
        if (shop == null) {
            stringRedisTemplate.opsForValue().set(key,"", RedisConstants.CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop), RedisConstants.CACHE_SHOP_TTL, TimeUnit.MINUTES);
        return shop;
    }
    private boolean tryLock(String key){
        Boolean aBoolean = stringRedisTemplate.opsForValue().setIfAbsent(key, "", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(aBoolean);
    }
    private void unlock(String key){
        stringRedisTemplate.delete(key);
    }

    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if(id != null) {
            return Result.fail("店铺id不能为空");
        }
        updateById(shop);
        stringRedisTemplate.delete(CACHE_SHOP_KEY+id);
        return Result.ok();
    }
}
